📰 Add a spinner to indicate content is loading

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ProgressIndicatorView.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ProgressIndicatorView.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ProgressIndicatorView.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ProgressIndicatorView.java
new file mode 100644
index 0000000000000000000000000000000000000000..7ef48e8a0b6d71ea3a8f7e4af71cc0f6f5632748
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+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ProgressIndicatorView.java
@@ -0,0 +1,82 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.ntp.cards;
+
+import android.content.Context;
+import android.support.annotation.ColorRes;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.ImageView;
+
+import org.chromium.base.ApiCompatibilityUtils;
+import org.chromium.chrome.R;
+import org.chromium.third_party.android.swiperefresh.MaterialProgressDrawable;
+
+/**
+ * Displays an indeterminate circular spinner, similar to {@link android.widget.ProgressBar} in
+ * Lollipop+. This class allows to backport the Material style to pre-L OS versions.
+ *
+ * It stays invisible for the first 500ms when shown, to avoid showing a spinner when content
+ * can load very quickly.
+ */
+public class ProgressIndicatorView extends ImageView {
+    private static final int SHOW_DELAY_MS = 500;
+    private final Runnable mShowSpinnerRunnable;
+
+    private final MaterialProgressDrawable mProgressDrawable;
+    private boolean mPostedCallback = false;
+
+    /**
+     * Constructor for use in layout files.
+     */
+    public ProgressIndicatorView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+
+        mShowSpinnerRunnable = new Runnable() {
+            public void run() {
+                mPostedCallback = false;
+                show();
+            }
+        };
+
+        mProgressDrawable = new MaterialProgressDrawable(getContext(), this);
+
+        mProgressDrawable.setBackgroundColor(getColorAsInt(R.color.ntp_material_design_bg));
+        mProgressDrawable.setAlpha(255);
+        mProgressDrawable.setColorSchemeColors(getColorAsInt(R.color.light_active_color));
+        mProgressDrawable.updateSizes(MaterialProgressDrawable.LARGE);
+        setImageDrawable(mProgressDrawable);
+
+        hide();
+    }
+
+    public void show() {
+        if (mPostedCallback) return;
+
+        // Stop first to reset the internal state of the drawable.
+        mProgressDrawable.stop();
+
+        setVisibility(View.VISIBLE);
+        mProgressDrawable.start();
+    }
+
+    public void hide() {
+        mProgressDrawable.stop();
+        removeCallbacks(mShowSpinnerRunnable);
+        mPostedCallback = false;
+        setVisibility(View.INVISIBLE);
+    }
+
+    public void showDelayed() {
+        mPostedCallback = true;
+        // We don't want to show the spinner every time we load content if it loads quickly; instead
+        // only start showing the spinner if loading the content has taken longer than 500ms
+        postDelayed(mShowSpinnerRunnable, SHOW_DELAY_MS);
+    }
+
+    private int getColorAsInt(@ColorRes int colorId) {
+        return ApiCompatibilityUtils.getColor(getResources(), colorId);
+    }
+}